Alloy rims: Flashy, but damage can put you in a fix

Those pricey tire hubs are susceptible to road hazards, can be hard to replace -- and safety issues surround repairs.

Nothing looks hotter on a new car than oversized alloy wheels and low-profile tires, the look of a black rubber band around a sleek, highly polished aluminum rim.

Unfortunately, nothing is more vulnerable to the cruelties of the roadway than this combination, which has less protection from the pounding of potholes, road debris and occasional curbs.

I have written recently about the problem of high-performance tire failures due to road hazards, but aluminum or alloy wheels are every bit as vulnerable and carry an even higher cost to the unsuspecting car owner.

At the least, rubbing against a concrete curb can deliver a cosmetically devastating "curb rash" to a $1,000 alloy wheel. At the most, a pounding from a pothole can bend the rim or chink off a few inches of the rim lip. (The lip is the surface of the wheel that forms a seal with the tire bead, keeping it airtight. It's a piece of metal that guarantees the safety of the entire vehicle.)

I don't know of any organization that keeps track of how many alloy wheels are clobbered every year on the road, but I'll make an educated guess that it approaches a million.

Once your prized alloy wheel is damaged, your choices are limited: Replace the wheel with an identical design, pick up one that doesn't match, buy an entire new set of wheels or repair the damaged wheel.

In some cases, particularly on a car that is more than a couple of years old, it is difficult to find an identical alloy wheel, particularly one that was an option or an aftermarket purchase. Lots of vendors offer alloys on the Internet and junkyards are another source, but usually a damaged rim will put a car out of commission and few people have days to search around for a replacement.

Buying a wheel that doesn't match is about as downscale as you can get. Conversely, buying four new alloys will set you back hundreds or thousands of dollars, making downscale seem an attractive alternative. If you're lucky, you have a full-size spare with an identical alloy wheel that you can use, and just replace that with a non-matching wheel.

Let's look more closely at alloy repairs. Plenty of companies have popped up to repair alloy wheels, saying that they take almost any banged-up aluminum rim and return it to an acceptable condition. Some experts are not convinced it's a good idea, however.

Alloy wheels have been around for a long time, though they have gained overwhelming popularity in the last 10 years. But the industry is still struggling with the difficulty of casting aluminum for the demanding loads imposed on a wheel. An academic paper published in the journal of the Minerals, Metals and Material Society only a year ago acknowledged, "Defects in automotive aluminum alloy casting continue to challenge metallurgists and production engineers as greater emphasis is placed on product quality and cost."

The engineering professors who wrote the paper examined "a range of casting-related defects found in low-pressure die-cast aluminum wheels" from a sample of several industrial plants. They found pores and other kinds of imperfections.

If you take those issues and compound them with road damage and then hand a wheel over to an unregulated repair facility, what you have is today's status quo.

The federal government's main automotive safety agency, the National Highway Traffic Safety Administration, has no standards or guidelines on the safety of repairing alloy wheels. As in so many other critical areas of car safety, the agency has not provided advice to consumers on any aftermarket products or issues. Notably, the province of British Columbia has adopted repair guidelines. Thank goodness for the Canadians.

But here, the matter is largely left to industry self-regulation and the decisions of companies about what they will repair or not. In general, there seem to be few wheels they will not repair. Their ads feature comely models, draped around either alloy wheels or the proprietors.

One major alloy repair factory boasts, for example, that it can handle 95% of the damaged wheels sent by consumers. Another repair operation boasts, "Yes, we can repair severely damaged wheels." Yet another company asserts, "If we can't do it, nobody can."

I'm not sure I'd bet my life on that kind of silly bravado. Neither would Ken Zion, an automotive collision expert who conducted a study of alloy wheel repair for a major insurance company. What he found troubles him a lot.

Zion says he would never repair an alloy wheel, other than polishing out minor scuff marks. But he routinely sees machining of dings and scrapes that take 40 thousandths of an inch or more off the rims.

"If you think about it, why would an alloy wheel manufacturer make a rim a certain dimension if they could save money by taking 10 thousandths or 20 thousandths off? So what makes somebody who comes along later to repair that wheel think they can safely remove that material or more?" Zion asked.